if you eliminate the crossing, and just use the switches it should fit. especially if you use the #6 crossovers. if you use the 18r switches for your crossover, you need to push the table width out a couple inches. i don't advise going smaller than 18r under any circumstances except for trolleys.

Ok, can anyone tell, me if mal (OP) was to pull this off on a 4 x 8 space, would mal have to use a curve with a radius of less than 18" for his inside loop?

Thanks much,

-jb

jb-

No. It's possible to have nested loops on a 4x8 without going less than 18" radius curves. The layout I built for my grandson has two nested loops and a third track which serves as a yard lead and there are no curves tighter than 18" radius.

Jeff, I take it when you say 18R switches, you are referring to "snap switches" as opposed to #4s or up, correct? Luckily no trolleys on the layout but I would like to stick with no less than 18R bc I do have a couple of old time SD45s that run fine on my 18R track and 18R switches.

I have nested loops now, using just snap switches to accomplish that on my layout section that is 4 x 8-I was wondering about using Mal's idea and if it would work, making the crossover using the same space. On the back of a package for an Atlas #4 turnout, instructions are given how to make one, using 4 #4s but they also instruct using a 25 degree crossover, not a 30. I wondered how much this mattered. Ideas???

Jeff, I take it when you say 18R switches, you are referring to "snap switches" as opposed to #4s or up, correct? Luckily no trolleys on the layout but I would like to stick with no less than 18R bc I do have a couple of old time SD45s that run fine on my 18R track and 18R switches.

I have nested loops now, using just snap switches to accomplish that on my layout section that is 4 x 8-I was wondering about using Mal's idea and if it would work, making the crossover using the same space. On the back of a package for an Atlas #4 turnout, instructions are given how to make one, using 4 #4s but they also instruct using a 25 degree crossover, not a 30. I wondered how much this mattered. Ideas???

Thanks again.

-jb

you are correct that the 18r switches are the "snap switches" from atlas, and their equivalents from others. these would also be the ones included in the layout expander packs. their geometry is very close no matter what brand you use.

the numbered switches, however, are completely different between manufacturers. so the angle of the crossing matters a great deal. for example, the atlas 4 is actually a #4.5 with a frog angle of about 12.8 degrees. thus they have 12.5 and 25 degree crossings designed to be used with their 4s. the bachmann 4 is about 14.5 degrees, give or take. so it needs about a 29 degree crossing. a 30 is close enough to work.

another difference between the two brands is that atlas has designed their switches to make crossovers and yard tracks on 2" centers. they did this by eliminating most of the track beyond the frog. with the crossings, they have trimmed the length so that only the track around the diamond remains. thus a 25 degree crossing measures about 4.5 inches in length as opposed to bachmann's 30 degree which is 9" bachmann switches are also singnficantly longer, with much more track beyond the frog.

the net effect of this is that a crossover using atlas 4s takes up 16" on 2" centers, and a scissors type double crossover takes up 20.5" on 3" centers. this is actually similar to a regular crossover using bachmann 4s which is 19.5" long on 3.25 " centers.

for the scisssors crossover using bachmann 4s and a 30 degree crossing, the length is 31" and the track centers are 7" apart.believe it or not this is less than the same type of crossover using atlas 6s, which works out to 26" long on 3" centers.

that extra space is why i had suggested earlier trimming some track off each leg on the crossing, and possibly the switches themselves, to get the track centers down to a more reasonable distance.

Bal, if you wouldn't mind doing that, that would be awesome! Thank you.

Jeff, I knew that about the "snap switches" but did not know that about the numbered turnouts. Thank you for the information Is there a difference in the geometry of the Bachmann turnouts you are speaking of, between the ones they make now with roadbed and the older ones they used to make w/o the roadbed? Another question, I have only seen numbered turnouts in the "old style" made by Atlas and a few other manufacturers but don't recall seeing them made by Bachmann-did they make them in the non roadbed version?As always, thank you for your assistance.

No. It's possible to have nested loops on a 4x8 without going less than 18" radius curves. The layout I built for my grandson has two nested loops and a third track which serves as a yard lead and there are no curves tighter than 18" radius.

Sounds like the layout my grandpa built for me when I was a little shaver.

Wish I had thought to make an exact track plan before it was disposed of years ago.

here ya go..two plans done real quick in Anyrail. Both use the #6 Crossovers the outside loop is 22", the second is 20" -using 22's & 18's alternating,and the inside loop is 18". So with both of these plans you could have 3 trains running, two circling and one doing yard work. =) You could put a third isolated loop in with 18's, I guess if you wanted that to be a trolly or something,but you couldn't get to the outer two tracks with it and it would have to have it's own power supply. Anywho, there ya go! Both of these layouts are on a 4x8 board. Question answered! B.